This invention relates to a coordinate input apparatus and, more particularly, to a coordinate input apparatus which employs the touch-panel system.
A coordinate input apparatus consists of a coordinate input element which detects the coordinate input position and a coordinate display element which display a pixel at a position corresponding to the coordinates detected by the coordinate input element. An example of the coordinate input apparatus employing the touch-panel system for the coordinate input element is described in U.S. Pat. No. 4,220,815.
A conventional touch-panel type coordinate input apparatus will be described in the following with reference to FIGS. 1 and 2. In FIG. 1, symbol 1' generically denotes a coordinate input element, and symbol 9' generically denotes a coordinate display element employing the cathode ray tube (CRT) system or the liquid crystal system.
A transparent glass plate 2' which constitutes part of the coordinate input element 1' has its top surface coated by vapor deposition with a lower coordinate detecting electrode 3' made of transparent conductive material (e.g., indium oxide tin). The glass plate 2' is confronted with a certain spacing 5' by a transparent upper sheet 4' of the type of a flexible touch panel, and the lower surface of the upper sheet 4' is coated, in the same way as of the lower coordinate detecting electrode 3', with an upper coordinate detecting electrode 6' extending in the intersectional direction. In the figures, symbol 4a' denotes a boss which maintains a spacing between the glass plate 2' and the upper sheet 4', and the upper sheet 4' with its lower surface provided with the bosses 4a' and the upper coordinate detecting electrode 6' are assembled as shown in FIG. 2.
In FIG. 2, the bosses 4a' extruding on the lower surface of the upper sheet 4' are pushed out below the upper coordinate detecting electrode 6' by using a punch 8', and dimples formed on the upper sheet 4' by punching are filled with transparent material 7', e.g., polyurethane coating. The coordinate input element 1' (glass plate 2' up to the upper coordinate detecting electrode 6'), which is the confronting disposition of the upper and lower coordinate detecting electrodes 6' and 3', is mounted over a coordinate display element 9' emplying the CRT system or liquid crystal system, as shown in FIG. 1, and through the touch by the finger tip so that the upper sheet 4' of the coordinate input element 1' sinks flexibly, the upper coordinate detecting electrode 6' comes in contact with the lower coordinate detecting electrode 3', causing the generation of a coordinate input signal by their switching action.